Wiring a Plug: Replacing a Plug and Rewiring Electronics

How to wire a new plug safely

Wire plugs correctly to maintain polarity (and safety!), that is, the correct path for the voltage-carrying hot wire and the neutral wire.

By the DIY experts of The Family Handyman Magazine
:September 2000

Step-by-Step

Wire a plug to maintain correct polarity

Wiring a new plug isn't difficult, but it's important to get the hot and neutral wires connected to the proper prongs. The danger isn't fire. The worry is that a miswired plug poses a fairly serious shock hazard. The key is
to make sure you connect the wires to
the proper terminals in the plug. The
wide prong on the plug links the
threaded base of light bulbs to the
neutral terminal (the wider slot) in the
receptacle. If the wires are reversed, the
hot side of the outlet (the side that can
deliver a shock) is wired to the
threaded socket. Normally there's a
cardboard insulator isolating the base
from the socket. However, if the
cardboard insulator is worn
out (common on old lamps),
the metal parts of the lamp
also could become “hot”(charged). You can then get a dangerous shock if you touch the
metal, which is easy to do when you're
“grounded” and changing a dead bulb.
For example, if you're standing on
damp concrete or in contact with a
radiator or other plumbing pipe while
you’re touching a miswired lamp, you
could get a dangerous jolt of electricity.

Buy a “polarized” replacement plug,
that is, one that has a normal prong
and a wide one. The neutral line on the
lamp cord is the one that’s odd; it’ll
have ribbing, a sharp ridge or printing
on it. If the cord is translucent, the
neutral is silver. The wire that goes to
the narrower prong has a smooth, plain surface or is gold in color.

Properly wired plug and lamp socket

Properly wired plug and lamp socket

Maintain the correct hot and neutral electrical paths from the outlet to the light bulb.

CAUTION

When connecting an electrical wire
to a screw terminal, always wrap the
wire clockwise around the screw. When
wrapped correctly in
a clockwise direction,
the wire will be pulled
tighter as you tighten the screw.
This results in a much more solid,
safer connection.